lay your shroud on your table with the motor mount bolted to it place a card (playing card ) in the shroud place your motor with the fan bolted to the motor set the fan in place on the card (the card is a shim) with the motor on the lugs it will be vertical use your gp engine mount locator to center the holes from your lugs to the mount once everything is bolted in place pull the fan in and out to check your end play remove the glow plug slowly turn the fan pulling on it through the shroud to make sure nothing rubs if it does lay a peice of sand paper on your bench and draw the face of the fan across the paper dont rub it back and forth just pull it across one way that should get you with in about 40/1000 the thickness of the card good luck donniercjet